Dismal Creek Watershed

Giles and Bland Counties, Virginia

September, 1999

General

The Dismal Creek Watershed occupies a basin formed by the slopes of Flat Top, Sugar Run and Brushy Mountains. As previously indicated ( see Land of Bowed Mountains ), the geologic structure of the region is broadly synclinal, so the basin is comprised solely of Silurian and Devonian rocks, excluding the older Ordovician formations which lie beyond the basin's mountain rim. Elevations range from 4000 feet ( 1220 meters ) on Sugar Run Mountain to 2000 feet ( 610 meters ) where Dismal joins Kimberling Creek. Since the latter is a branch of Walker Creek, the Basin is part of the New River System.

Although aspects box the compass in the basin, the forest and vegetation types found in our inventories appear more to reflect the geology than slope exposure.

Flat Top Mountain slopes, where most Dismal Creek branch streams originate, are dominated by Silurian rocks of the Keefer Sandstone and Tonoloway Limestone, which have been mapped by Rader and Gathright ( 1986 ) as " undivided". However, infolded or down-faulted in this complex are erosion remnants of the overlying Devonian Rocky Gap Sandstone which, significantly,is calcareous in part. It is this sandstone that has been interpreted to be present or exert its influence where some calcareous seep plant communities occur, which have been inventoried by the Virginia Natural Heritage Program (Erdle et al ,1996) and by us as reported here.Despite such alkaline enclaves, which may also in part be attributable to Tonoloway Limestone, that section of the watershed observed by us appears to be constituted dominantly of silicious rocks and acid soils.Indeed a salient characteristic here is the juxtaposition of alkaline and acid microhabitats and individual calciphile and acidiphile plants.

Although our inventories in general fell within the Dismal Creek basin, one traverse originated on Ordovician rocks on the southeast side of Brushy Mountain, in the Kimberling Creek water gap. However this traverse soon entered the Dismal Creek watershed along the Appalachian Trail.

The Dismal Creek watershed also contains habitat for one of the rarest endemic Appalachian species, the shrub Piratebush ( Buckleya distichophylla ). Colonies of this shrub, which is a hemiparasite on Hemlock and perhaps other plants, are found along the Dismal Creek mainstem and one of these colonies was newly discovered during our inventory. Except for this colony of Piratebush, all of our inventories were conducted in the Jefferson National Forest.

Dismal Creek slopes

Source walks: 6-11-97 and 6-12-97

Inventories of several wetlands and associated upland forest were conducted along Forest Road 201 of the Jefferson National Forest. The best known of these wetlands is a calcareous seep just east of the road crossing of Pearis Thompson Creek,a branch of Dismal. The elevation here is near 2300 feet ( 700 meters) asl and the aspect south to southwest with a steep slope near the road rising to a bench. A sandstone outcrop here effervesces to acid and presumably is the source of the seep. The location is just upstream from a prominent falls on Dismal Creek, the Falls of Dismal. Like many parts of this watershed,the forest here has a youthful canopy. In the vicinity of the seep this consists of White Pine, Adelgid-free Canada Hemlock, Black Birch, Red Maple, Tuliptree, Black Oak, Northern Red Oak and Table Mountain Pine. Also common here is a species uncommon to the Central Appalachians, namely Arborvitae or Northern White Cedar (Thuja occidentalis ). Here associated with the calcarious seeps and sandstones, this boreal tree is usually confined to limestone cliffs in the Appalachians. Within the acidic upland forest Sourwood ( Oxydendrum arboreum ), a little Striped Maple ( Acer pensylvanicum ) and Flowering Dogwood (Cornus florida ) form an understory and Alternate-leaved Dogwood ( Cornus alternifolia ) and Great Rhododendron ( Rhododendron maximum ) a shrub layer, with Rhododendron concentrated along the stream.

The nearby small stream ,Pearis Thompson Creek, which descends in a rocky bed, is overshadowed by Hemlock, Arborvitae, Red Maple, Tuliptree and other mesic species, including Great Rhododendron. While the latter and Red Maple do not occur in the calcareous seep, they and Arborvitae form remarable associations in the stream bed and on its banks. In one place less than 100 feet ( 30 meters ) from the seep, a small Rhododendron was observed emerging from between the roots of a six inch ( 15 cm ) diameter Arborvitae while nearby a Red Maple grew from the steep bank inches above an Arborvitae. Little or no reaction with acid was obtained from sandstone exposures in the vicinity of these occurrences. However, interesting questions are posed by the close association of species with acid and alkaline affinities.

An additional species of great interest that was reported as part of the seep community ( Erdle et al, 1996 ) is Showy Ladyslipper ( Cypripedium reginae ), while the rare endemic Torrey's Mountain Mint ( Pycnanthemum torrei ) is to be found only a short distance away along the road.

Fauna in the seep vicinity were represented by frequent calls of Scarlet Tanagers ( Piranga olivacea ) and a black and white patterned Dragon Fly that had evidently just emerged and was hovering in place with rapid wingbeats less than a meter above the seep.

A brief survey of the forest floor on the opposite ( down-slope ) side of the road also disclosed numerous leaf rosettes of Hybrid Bunchflower ( Melanthium hybridum ), a species not observed at or above the seep.Farther up slope, perhaps 300 feet ( 100 meters ) from the calcareous seep, there is a more extensive but still small acid seep area that was inventoried by us in light rain on 6-12-97. The canopy in the seep area consists of Red Maple, Black Gum and White Pine, although the area is for the most part open. A number of large fallen trees, mostly Red Maple, perhaps illustrate how the seep is kept open by permitting only shallow rooting of trees. However there is a prominent shrub layer with Smooth Alder, Spice Bush, Alternate-leaved Dogwood, Mountain Laurel, Great Rhododendron, Maleberry, Shrubby St. Johns-wort and Wild Raisin ( Viburnum cassinoides ).

The herb layer of this wetland was dominated by sedges. Some of these, like the abundant Carex intumescens and C. gynandra , are acidiphile, a minority,such as C. flava and C. granularis, calciphile, while the majority, including C. angustior, C. gracillima, C. tetanica, C.lurida, the bulrush Scirpus atrovirens and a species of spikerush (Eleocharis sp ), are either of widespread occurrence or of indefinite association. An additional species ,Carex emoryi, a southern form of C. stricta, appeared to be more at home in the shade, where it formed tall and luxuriant tussocks. Of related interest was an emerging dragon fly observed on Carex angustior in excellent concealment by its resemblance to the spike of this sedge.

The upland forest above this wetland appeared, if anything, more acidic than that down slope, with abundant Teaberry and Galax. However as indicated previously, the slope between the two seeps contains minor seeps which have calciphile plants, albeit in degraded form, and it appears that alkaline and acid seeps merge there.

Dismal Creek/ Brushy Mountain

Source Walk: 6-12-97

Our traverse,in the afternoon of the 12 th, began where the Appalachian Trail intersects State Route 606 along Kimberling Creek. From there it followed the AT, obliquely ascending the northeast side of the water gap to perhaps 2500 feet ( 760 meters) asl. Still following the trail, it curved around the mountain crest on a descending course to the intersection with the Falls of Dismal trail. The latter was then followed to the Falls and FR 201 beyond. In terms of vegetation and forest type the traverse consisted of three parts: initially through acid/mesic forest dominated by immature pine and more mature Beech and other trees, then through a short, less acidic,mesic section and finally through a long extent of xeric and acidic forest along the northwest slope of Brushy Mountain. In what follows species and terrain features noted during the traverse will be listed in the order in which they were encountered.

The first section of the traverse was over terrain that in all probability is underlain by Upper Ordovician rocks ( Rader and Gathright, 1986 ). Some of these rocks may contain carbonate, although no evidence of such was seen, and, in fact, due to negligence or otherwise, our notes contain no references to rocks in this section. The canopy here consists of mixed conifer and deciduous trees. Virginia Pine, perhaps dating to early agricultural clearing, is being overtopped by other species. Most common among the latter are Canada Hemlock ( Tsuga Canadensis ), White Pine, Beech, Black Gum, Red Maple, Black Birch and Black, Scarlet and White Oaks. Sourwood is common in the understory and Yellow Buckeye ( Aesculusoctandra ) seedlings were seen. Of special interest is the occurrence of American Holly ( Ilex opaca ), then in bloom, as trees to perhaps 15 feet (4 meters ) in height, but with few seedlings. Great Rhododendron is the dominent shrub but Mountain Laurel, Chinquapin and Pasture Rose are also present. Herbs sequentially encountered were Ground Pine ( Lycopodium flabelliforme ), Rattlesnake Weed ( Hieracium venosum ), the southern sedge Carex flaccosperma, then C. bushii, C. wildenowii, a wedge grass (Sphenopholis sp ), White Wood Aster ( Aster divaricatus ), Late Purple Aster ( Aster patens ), Galax, abundant Teaberry, Mountain Bellwort ( Uvularia pudica ), Creeping Five-leaf ( Potentilla simplex ), Yellow Stargrass and Carex digitalis. These were followed by American Chestnut sprouts, increasing amounts of Deerberry ( Vaccinium stamineum ), Sourwood and the fungal species of Clitocybe, Hygrophorus and Amanita. A seep area contained Virginia Bugleweed ( Lycopus virginicus ), which was in dryer areas followed by Table Mountain Pine, Common Greenbrier ( Smilax rotundifolia ), Summer Grape ( Vitis aestivalis ), Shrubby St. Johns-wort, Carex swanii, Wild Vetch ( Vicia caroliniana ), Whorled Loosestrife ( Lysimachia quadrifolia ) and a little Bracken Fern ( Pteridium aquilinum ).

At this point we entered the short stretch of richer and less acidic mesic forest. Here the canopy consisted mostly of youthful but tall Tuliptree, Black and White Oaks with a great variety of mesic herbs. A few of the latter noted in our relatively rapid passage were minor amounts of Marginal Shield Fern ( Dryopteris marginalis ), attractively-blooming Violet Wood Sorrel ( Oxalis violacea ), Black Cohosh ( Cimicifugaracemosa ) and Enchanters Nightshade ( Circaea quadrisulcata ). Wood Peewes ( Cantopus virens ) and Pine Warblers ( Dendroica pinus ) were identified birds and the soil was noted as a deep, rich mull. It is likely that this tract of mesic forest occupies the uppermost of the more hospitable Ordovician rocks in the section. It was in any case followed by the ridge crest and more xeric and acidic forest. This latest change in vegitation may have have resulted in part from the southwest aspect but likely also from the Tuscarora Sandstone that crowns the ridge. Here at perhaps 2500 feet ( 760 meters ) asl there was a dramatic increase in White Pine-perhaps heralded by the previously-noted Pine Warbler-in association with Black and White Oaks, Black Gum, more Deerberry ( here in bloom ), greatly increased frequency of Upland Low Blueberry and the first noted Wood Tickseed ( Coreopsis major ). Although we did not see them, the calls of a number,perhaps a family group, of Piliated Woodpeckers ( Hylatomus pileatus ) rung out from the nearby canopy.

Descending now through increasingly dry and acidic forest we noted a reddish sandstone, perhaps the Keefer, which bore the Skolithus fossils that are said to characterize that formation. Associated soils had a well-developed mor layer under a ground cover of Teaberry, Trailing Arbutus ( Epigaea repens ) and various Blueberries, while Chestnut Oak dominated the canopy.

Dr. R. Hunsucker and Pirate Bush, Dismal Creek, 6-12-97.

At several places the trail approaches closely to Dismal Creek, where Great Rhododendron forms dense thickets. However in a place free of Rhododendron but under the canopy, we encountered our first Pirate Bush. This colony, first reported by the Natural Heritage Program, did not appear to be flourishing and consisted of only a few shrubs.

After reaching the junction with the Falls of Dismal Trail we proceded down it to the Falls. On the way the forest continued dry and ericaceous and along it we identified our first Cow Wheat ( Melampyrum lineare ) and Carolina Lily ( Lilium michauxii ), both of which are characteristic of this habitat. As the falls was approached Great Rhododendron and other mesic species increased in frequency and on the cliff at the Falls this Rhododendron again shared the sandstone with Arborvitae, and as elsewhere, appeared to grow above the latter but in close proximity.

On the ravine slope on the opposite side of the stream, the forest was initially quite mesic but became dryer as the road was approached higher up. Here we noted two plants, that in immature and non-fruiting forms resemble each other closely. Characteristic of the moister habitat near the stream was Lovage ( Ligusticum canadense ), while equally so of the dryer upper slope was Wild Sarsaparilla ( Aralia nudicaulis ). Usually associated with cool habitats, the latter is one of the few markedly northern species observed in the region's upland forests at the elevations inventoried. The two species may be easily distinguished however, by the characteristic and strong odor of Lovage's crushed foliage.

Although no systematic inventory was done of the streamside vegetation along Dismal Creek, a species conspicuous in the Falls area was Fringe Tree ( Chionanthus virginica ), then in full bloom. Additional species reported as occurring along the stream ( Erdle et al, 1996 ) were Smooth Alder, Silky Dogwood ( Cornus amomum ), Kidney-leaved Grass of Parnassus, Michaux Bluets ( Houstonia serpyllifolia ), Twisted Sedge ( Carex torta ) and Tasselrue ( Trauvetteria caroliniensis ). An unidentified willow was also seen by us.

Fringe Tree in bloom, Dismal Creek, 6-12-97.

On returning to our vehicle in the water gap our walk took us to where FR 201 passed close to the stream in an essentially residential area. Here unexpectedly, at the edge of mowed roadside grass, on the stream bank, we found a substantial colony of Piratebush. This colony exhibited vigorous growth, with some shrubs as high as ten feet ( 3 meters ) and accompanied by seedings or sprouts.This Piratebush was associated with Canada Hemlock, Black Birch, Northern Red Oak, White Ash, Red Maple and Sassafras, with a shrub layer of Witch Hazel, Great Rhododendron and another hemiparasite, Buffalonut ( Pyrularia pubera ). Numerous vines, including Saw Brier, Common Greenbrier, Virginia Creeper ( Parthenocissus quinquefolia ), Poison Ivy ( Rhus radicans ) and Bittersweet ( Celastrus scandens ) flourished in the edge habitat.

Dismal Creek/Walnut Flats

Source Walk:6-11-97,6-12-97 and 6-13-97

During our time at the Walnut Flats Campground of the Jefferson National Forest as much effort as possible was made to famiiarize ourselves with the vegetation surrounding the campground and at a nearby artificial pond. The forest here is prevailingly acidic and dry, but with acid/mesic parts, particularily along a swale which was dammed to create the pond. The canopy, which is mostly young, except for scattered old trees, included, in rough order of abundance, White Oak, White Pine, Red Maple, Mockernut and Pignut Hickories, Scarlet Oak, Sassafras, Tuliptree, Hemlock and a little Sugar Maple. Black Walnut occurs only on the flat area of the campground, which may be underlain by carbonate or other more nutrient-rich rock. Sourwood is common in the understory of the acidic forest where it is accompanied by Flowering Dogwood and American Holly up to 10 feet ( 3 meters ) tall. Other small trees and shrubs noted were Alternate-leaved Dogwood, Blackhaw Viburnum ( Viburnum prunifolium ), American Hazelnut and Spice Bush in moist areas, and in dry areas, Upland Low Blueberry. Smooth Alder and possibly other wetland shrubs occur in the pond area. Virginia Creeper was a common vine.

Royal Fern was abundant in the acid swale which also contained Carex gynandra and C. intumescens. Wild Sage ( Salvia lyrata ), then in bloom, flourished in the dryer forest areas. A spot inventory of the slope forest just northwest of the campground yielded White Pine, White Oak. Pignut Hickory, Red Maple a large Sugar Maple, Sassafras, Hemlock, Tuliptree,American Holly, American Hazelnut, Upland Low Blueberry, Teaberry and Four-leaved Yam in an area with a heavy leaf mat and few small plants. Several species later identified from the pond area were Variable Pondweed ( Potamogeton diversifolius ), Carex laevivaginata and C. flava, the last-named being the rare northern disjunct reported earlier for the seep areas.

A virtual constant at the campground during the evenings and nights were the calls of Spring Peepers ( Hyla crucifer ) and Bullfrogs ( Rana catesbyiana ) from the pond area. Lesser Gray Treefrogs ( Hyla chrysocelis ) also called from trees at times. In the evenings Wood Thrush ( Hylocichla mustelina ) were heard, but never close to the camp area. Red-eyed Vireos ( Vireo olivaceus ) were as usual in evidence by their calls, as were American Robins ( Turdusmigratorius ), Tufted Titmice ( Parus bicolor ) and Pileated Woodpeckers, with the latter, as judged by call volume, a family group. On the evening of 6-12-97 we thought we had heard a Woodcock ( Philohela minor ), but this is very uncertain and even unlikely. During late evening of 6-11-97 a single hoot and a shriek, possibly from a Barred Owl ( Strix varia ), sounded nearby. On visiting the pond at dusk on 6-12-97 we saw many large ( 3 inch/8 cm ) polywogs, likely Bullfrog, small fish of similar size, a Newt ( Notophthalmus viridescens ) and on a stem of tall grass on the water's edge, a pair of long-legged spiders of the genus Tetragnatha. The female of this spider was near two inches in total length. At this time we also saw a number of bats circling above the pond at various heights. To our disappointment however, we heard no Whip-poor-wills ( Caprimulgus vociferus ) during our visit here, surely a sign of forest degradation either here, in the tropics,or both.

The character of that part of the watershed inventoried by us is markedly Southern Appalachian with Arborvitae, Wild Sarsaparilla and Round-leaf Pyrola representative of the few resident northern upland species, although several sedges in the wetlands are northern disjuncts. The low incidence of characteristic northern species may be explained by topography unfavorable to cold air drainage and accumulation since there are no high slopes and few valley flats in the area inventoried.